US7212509B1 - Method for regulating a frequency offset in a base-station receiver of a data communications system - Google Patents

Method for regulating a frequency offset in a base-station receiver of a data communications system Download PDF

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Publication number
US7212509B1
US7212509B1 US10/069,196 US6919600A US7212509B1 US 7212509 B1 US7212509 B1 US 7212509B1 US 6919600 A US6919600 A US 6919600A US 7212509 B1 US7212509 B1 US 7212509B1
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United States
Prior art keywords
frequency
base station
subscriber station
converter
modulator
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Expired - Fee Related, expires
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US10/069,196
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English (en)
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Wolfgang Bodenschatz
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Ericsson AB
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Marconi Communications GmbH
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    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03D—DEMODULATION OR TRANSFERENCE OF MODULATION FROM ONE CARRIER TO ANOTHER
    • H03D7/00—Transference of modulation from one carrier to another, e.g. frequency-changing
    • H03D7/16—Multiple-frequency-changing
    • H03D7/161—Multiple-frequency-changing all the frequency changers being connected in cascade
    • H03D7/163—Multiple-frequency-changing all the frequency changers being connected in cascade the local oscillations of at least two of the frequency changers being derived from a single oscillator
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03J—TUNING RESONANT CIRCUITS; SELECTING RESONANT CIRCUITS
    • H03J1/00—Details of adjusting, driving, indicating, or mechanical control arrangements for resonant circuits in general
    • H03J1/0008—Details of adjusting, driving, indicating, or mechanical control arrangements for resonant circuits in general using a central processing unit, e.g. a microprocessor
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03J—TUNING RESONANT CIRCUITS; SELECTING RESONANT CIRCUITS
    • H03J7/00—Automatic frequency control; Automatic scanning over a band of frequencies
    • H03J7/02—Automatic frequency control
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00—Modulated-carrier systems
    • H04L27/0014—Carrier regulation
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00—Modulated-carrier systems
    • H04L27/0014—Carrier regulation
    • H04L2027/0016—Stabilisation of local oscillators
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00—Modulated-carrier systems
    • H04L27/0014—Carrier regulation
    • H04L2027/0018—Arrangements at the transmitter end
    • H04L2027/0022—Arrangements at the transmitter end using the carrier of the associated receiver of a transceiver

Definitions

  • the present invention concerns a method for correcting frequency offset in the receiver of a base station of a data transmission system, in which the base station transmits data in time multiplex to several subscriber stations, and data transmission from subscribers to the base station occurs in time multiplex with multiple access.
  • a point-to-multipoint radio transmission system is known from DE 196 35 533 A1 in which data transmission occurs between a base station and several subscriber stations in time multiplex (TDM/TDMA).
  • the base station and subscriber stations are essentially designed the same and have in their transmission branch a modulator, one or more intermediate frequency (IF) stages and a high frequency (HF) stage, and similarly in their receiving branch an RF stage, one or more HF stages, and a demodulator.
  • the IF and RF stages, and the modulator and demodulator each have a converter controlled by a reference frequency.
  • the reference frequencies are made available by local oscillators in corresponding frequency positions.
  • the base station delivers messages to a number of subscriber stations in the form of a continuous data stream multiplexed with reference to time.
  • Each of the existing subscriber stations sends its data to the base station in a time slot allocated to it individually.
  • data bursts therefore arrive from different subscriber stations according to a stipulated schedule.
  • the individual incoming data bursts must be demodulated as free of error as possible at the base station. To do this, it is essential that the receiver of the base station be locked onto the carrier frequency of the incoming data bursts with the greatest possible accuracy.
  • a prerequisite for this is that a frequency offset between the data bursts received by the base station and the frequency normal of the base station be as limited as possible, ideally zero.
  • the underlying task of the invention is therefore to offer a method of the type just mentioned by which a frequency offset can be corrected in the receiver of a base station with the least possible demands.
  • the reference frequency of the demodulator of each subscriber station is initially set so that its output signal has no carrier frequency fraction.
  • a reference frequency for the modulator in the subscriber station is then calculated from the reference frequency so set for the demodulator in the corresponding subscriber station and at all fixed converter reference frequencies in the base station under the condition that a carrier frequency occurring in the output signal of the demodulator of the base station and representing a frequency offset is set at zero.
  • the reference frequency for the demodulator of the subscriber station is finally set at the calculated value.
  • the reference frequency for the modulator need only be set in the individual subscriber station at a value that can be numerically calculated in simple fashion from known quantities.
  • the reference frequency for the modulator of the subscriber station is therefore calculated from the condition that the sum of the reference frequencies for the modulators, demodulators and intermediate frequency converters in the base station and in the subscriber station is set at zero, the reference frequencies for the RF converter in the receiving and sending branch being the same but of opposite phase both in the base station and in the subscriber station.
  • the reference frequencies in the base station and in each subscriber station for frequency conversion in the modulator and demodulator and for one or more intermediate frequency converters are preferably formed by a local oscillator by multiplying the local oscillator frequency by corresponding conversion factors, and reference frequencies for the RF converters are generated by an additional local oscillator by multiplying a local oscillator frequency by corresponding conversion factors.
  • the conversion factor for the modulator of the corresponding subscriber station is calculated from the condition that the sum of a first product, formed by multiplying the local oscillator frequency of the base station by the sum of the conversion factors for the modulator and demodulator and the intermediate frequency conversion factors in the receiving and sending branch, and a second product, formed by multiplying the local oscillator frequency of the subscriber station by the sum of the conversion factors for the modulator and demodulator and the intermediate frequency conversion factors in the receiving and transmitting branch, is set at zero.
  • the conversion factors for the RF converters in the receiving and transmitting branch in both the base station and subscriber station be equally large but of opposite sign.
  • the local oscillator frequency of the base station is preferably derived in the subscriber station from the symbol rate of the data transmitted from the base station to the subscriber station.
  • FIG. 1 shows a schematic of a base station
  • FIG. 2 shows a schematic of a subscriber station.
  • a transmitting/receiving circuit of a base station of a point-to-multipoint radio system is shown in FIG. 1 .
  • Data transmission occurs between this base station and several subscriber stations, the base station transmitting a continuous time-multiplexed (TDM) data stream to the subscriber stations, which access the data bursts in the time slots of the data stream allocated to them in time multiplex with multiple access (TDMA).
  • TDM continuous time-multiplexed
  • the individual subscriber stations also send their data in the direction of the base station according to the TDMA principle in fixed time slots.
  • a transmitting/receiving antenna AB belonging to the base station is shown in FIG. 1 . It can transmit data in several solid sectors in which the subscriber stations are located, or receive signals from these several sectors from the subscriber stations.
  • Each subscriber station one of which is shown as an example in FIG. 2 , has an antenna AC, which is aligned on the base station and can receive signals from it or send signals to it.
  • modulation signal x is modulated by converter UBM of a modulator onto a carrier that corresponds to a frequency of a first free-running local oscillator LO 1 multiplied by conversion factor a.
  • Frequency FBMT originating from converter UBM is fed to first intermediate frequency converter UBZ 1 T.
  • this converter UBZ 1 T receives the frequency of the first local oscillator LO 1 multiplied by conversion factor b.
  • the output carrier frequency fBI 1 T of first IF converter UBZ 1 T reaches the second IF converter UBZ 2 T.
  • This second IF converter UBZ 2 T is controlled by the frequency of first local oscillator LO 1 multiplied by conversion factor c.
  • a single stage, or more than two intermediate frequency stages can also be present, deviating from the depicted practical examples.
  • Output carrier frequency fBI 2 T of the second IF converter UBZ 2 T reaches the input of an RF converter UBRT.
  • the reference frequency for this RF converter is the frequency of second free-running local oscillator LO 2 multiplied by conversion factor d.
  • the transmitting frequency fBRT is available at the output of RF converter UBRT.
  • RF converter UBRR is present, to which receiving frequency fBRR is fed.
  • the reference frequency for this RF converter is again the frequency generated by a second local oscillator LO 2 multiplied by conversion factor d′.
  • Output carrier frequency fBI 2 R of RF converter UBRR lies at the input of IF converter UBZ 2 R.
  • IF converter UBZ 2 R is controlled by the frequency of first local oscillator LO 1 multiplied by conversion factor c′.
  • additional IF converter UBZ 1 R is also present in the receiving branch.
  • This converter UBZ 1 R converts carrier frequency FBI 1 R, delivered from the preceding IF converter UBZ 2 R by means of a frequency originating from the first local oscillator LO 1 and multiplied by conversion factor b′, to an intermediate frequency FBMR.
  • converter UBD of a demodulator that demodulates the received signal reduced to the intermediate frequency level.
  • converter UBD receives the frequency generated from local oscillator LO 1 multiplied by conversion factor a′.
  • the demodulated base band signal x′ is available at the output of the converter UBD.
  • a modulator is situated in the transmitting branch with converter UCM that modulates modulation signal y′ onto a carrier.
  • converter UCM of the modulator receives a reference frequency that corresponds to a frequency of first free-running local oscillator LO 4 multiplied by conversion factor h′.
  • Carrier frequency FCMT originating from converter UCM is fed to first intermediate frequency converter UCZ 1 T.
  • This IF converter UCZ 1 T receives as reference frequency the frequency of first local oscillator LO 4 multiplied by conversion factor g′.
  • Output frequency FCI 1 T of first IF converter UCZ 1 T reaches second IF converter UCZ 2 T.
  • This converter UCZ 2 T is controlled by the frequency of first local oscillator LO 4 multiplied by conversion factor f′.
  • the subscriber station can also be provided with only one intermediate frequency stage or there can also be more than two.
  • Output frequency fCI 2 T of second IF converter UCZ 2 T reaches the input of RF converter UCRT.
  • the reference frequency for this RF converter is the frequency of second free-running local oscillator LO 3 multiplied by conversion factor e′.
  • the transmitting carrier frequency FCRT is available at the output of RF converter UCRT.
  • RF converter UCRR to which receiving carrier frequency FCRR is fed, is present in the receiving branch of the subscriber station.
  • the reference frequency for this RF converter is again the frequency generated by second local oscillator LO 3 multiplied by conversion factor e.
  • Output carrier frequency fCI 2 R of RF converter UCRR lies at the input of IF converter UCZ 2 R.
  • This converter UCZ 2 R is controlled by the frequency of first local oscillator LO 4 multiplied by conversion factor f.
  • an additional IF converter UCZ 1 R is also present in the receiving branch.
  • This converter UCZ 1 R converts carrier frequency FCI 1 R, delivered from preceding IF converter UCZ 2 R by means of the frequency originating from first local oscillator LO 4 multiplied by conversion factor g, to intermediate carrier frequency FCMR.
  • a demodulator follows with converter UCD that demodulates the received signal reduced to the intermediate frequency level.
  • converter UCD receives the frequency generated by first local oscillator LO 4 multiplied by conversion factor h.
  • Demodulated received signal y is available at the output of converter UCD.
  • output frequency y is obtained from input frequency x of the transmitting branch of the base station and the reference frequencies for converters UBM, UBZ 1 T, UBZ 2 T, UBRT and the reference frequencies for the converters UCRR, UCZ 2 R, UCZ 1 R and UCD of the receiving branch of the subscriber station.
  • x+LO 1 ⁇ a+LO 1 ⁇ b+LO 1 ⁇ c+LO 2 ⁇ d+LO 3 ⁇ e+LO 4 ⁇ f+LO 4 ⁇ g+LO 4 ⁇ h y (1)
  • carrier frequency x′ is produced at the output of the modulator according to equation (2) from input frequency y′ of the transmitting branch of the subscriber station and the reference frequencies for converters UCM, UCZ 1 T, UCZ 2 T, UCRT of the transmitting branch of the subscriber station and the reference frequencies for converters UBRR, UBZ 2 R, UBZ 1 R and UBD of the receiving branch of the base station.
  • y′+LO 4 ⁇ g′+LO 4 ⁇ g′+LO 4 ⁇ f′+LO 3 ⁇ e′+LO 2 ⁇ d′+LO 1 ⁇ c′+LO 1 ⁇ b′+LO 1 ⁇ a′ x′ (2)
  • equation (4) follows from equation (3).
  • x′ LO 1 ⁇ ( a+b+c+a′+b′+c ′)+ LO 2 ⁇ ( d+d ′)+ LO 3 ⁇ ( e+e ′)++ LO 4 ⁇ ( f+g+h+f′+g′+h ′) ⁇ y (4)
  • a frequency offset in the base station is expressed by the fact that output signal x′ of demodulator UBD still has a carrier frequency fraction in addition to the base band signal.
  • the objective is to control the frequencies so that the frequency offset in the form of a carrier frequency fraction appearing at the demodulator output of the base station disappears.
  • This frequency offset is corrected merely by the fact that conversion factors h and h′ for demodulator converter UCD and modulator converter UCM are variable in the subscriber station and are set at the desired values h′* and h*.
  • the change in conversion factors h and h′ occurs by processor PZ.
  • the conditions in equations (6) and (7) state that the conversion factors d, d′ and e, e′ for the RF converter in the transmitting and receiving branch of the base station and the subscriber station are equally large but must have opposite signs. This means that the reference frequencies for the converters in the transmitting and receiving branches are equal but must have a phase shift of 180°.
  • a symbol rate SRC according to equation (11) is then received, which depends on the time basis of the local oscillator LO 4 .
  • SRC LO 4 /q (11)
  • Factor p is a defined value in the base station that is known to processor PZ in the subscriber station.
  • Processor PZ determines factor q by deriving the symbol rate SRC from the received signal y and relating it according to equation (11) to the known system clock frequency of the local oscillator LO 4 .
  • Equation (13) we finally obtain, from equation (9), equation (14), according to which processor PZ calculates the conversion factor h′* to be set.
  • the conversion factors a, b, c, a′, b′, c′, f, g, f, g′ occurring in equation (14) are fixed values and are known to processor PZ, which has also determined beforehand the new conversion factor h* for the demodulator.
  • h ′* ⁇ ( p/q ) ⁇ ( a+b+c+a′+b′+c ′) ⁇ ( f+g+h*+f′+g ′) (14)
  • the frequency synchronization discussed above is conducted between each of the subscriber stations and base stations.
  • An advantage of the described correction of a frequency offset in the base station consists of the fact that the local oscillators can be free-running. Flexible layout of the conversion factors is also possible so that considerable latitude is obtained for the choice of duplex frequency spacings.

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  • Engineering & Computer Science (AREA)
  • Computer Hardware Design (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Power Engineering (AREA)
  • Mobile Radio Communication Systems (AREA)
  • Digital Transmission Methods That Use Modulated Carrier Waves (AREA)
US10/069,196 1999-08-21 2000-08-15 Method for regulating a frequency offset in a base-station receiver of a data communications system Expired - Fee Related US7212509B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE19939811A DE19939811A1 (de) 1999-08-21 1999-08-21 Verfahren zum Ausregeln eines Frequenzoffsets im Empfänger einer Basisstation eines Nachrichtenübertragungssystems
PCT/IB2000/001179 WO2001015315A1 (de) 1999-08-21 2000-08-15 Verfahren zum ausregeln eines frequenzoffsets im empfänger einer basisstation eines nachrichtenübertragungssystems

Publications (1)

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US7212509B1 true US7212509B1 (en) 2007-05-01

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US10/069,196 Expired - Fee Related US7212509B1 (en) 1999-08-21 2000-08-15 Method for regulating a frequency offset in a base-station receiver of a data communications system

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US (1) US7212509B1 (de)
EP (1) EP1212830B1 (de)
CN (1) CN1382320A (de)
AT (1) ATE281709T1 (de)
AU (1) AU6463800A (de)
DE (2) DE19939811A1 (de)
NO (1) NO20020839L (de)
WO (1) WO2001015315A1 (de)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20110182410A1 (en) * 2008-05-22 2011-07-28 Vladimir Yegorovich Balakin Charged particle cancer therapy beam path control method and apparatus
US20110180720A1 (en) * 2008-05-22 2011-07-28 Vladimir Yegorovich Balakin Charged particle beam acceleration method and apparatus as part of a charged particle cancer therapy system
US8841866B2 (en) 2008-05-22 2014-09-23 Vladimir Yegorovich Balakin Charged particle beam extraction method and apparatus used in conjunction with a charged particle cancer therapy system
US8901509B2 (en) 2008-05-22 2014-12-02 Vladimir Yegorovich Balakin Multi-axis charged particle cancer therapy method and apparatus

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103368891B (zh) * 2012-04-05 2016-05-11 晨星软件研发(深圳)有限公司 信号处理装置及信号处理方法
CN103905800A (zh) * 2012-12-26 2014-07-02 凌阳科技股份有限公司 一种对邻频道干扰不敏感的快速盲扫方法

Citations (6)

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Publication number Priority date Publication date Assignee Title
US5287388A (en) * 1991-06-25 1994-02-15 Kabushiki Kaisha Toshiba Frequency offset removal method and apparatus
US5493710A (en) 1991-08-02 1996-02-20 Hitachi, Ltd. Communication system having oscillation frequency calibrating function
EP0713298A2 (de) 1994-11-21 1996-05-22 Sony Corporation Sender und Zweiwegfunkgerät
US5584066A (en) 1993-10-08 1996-12-10 Sony Corporation Correcting circuit for mixing circuit receiver using same and frequency spectrum inverting circuit using same
US5970102A (en) * 1996-08-24 1999-10-19 Samsung Electronics Co., Ltd. Circuit and method for detecting frequency correction burst in TDMA digital mobile communication system
US6266361B1 (en) * 1998-07-21 2001-07-24 Chung-Shan Institute Of Science And Technology Method and architecture for correcting carrier frequency offset and spreading code timing offset in a direct sequence spread spectrum communication system

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE19635533A1 (de) * 1996-03-27 1997-10-30 Bosch Gmbh Robert Punkt-zu-Mehrpunkt Fünkübertragungssystem
DE19748913B4 (de) * 1997-02-14 2004-09-30 Hewlett-Packard Co. (N.D.Ges.D.Staates Delaware), Palo Alto Sende-Empfangs-Vorrichtung für ein drahtloses Informationszugriffsystem

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5287388A (en) * 1991-06-25 1994-02-15 Kabushiki Kaisha Toshiba Frequency offset removal method and apparatus
US5493710A (en) 1991-08-02 1996-02-20 Hitachi, Ltd. Communication system having oscillation frequency calibrating function
US5584066A (en) 1993-10-08 1996-12-10 Sony Corporation Correcting circuit for mixing circuit receiver using same and frequency spectrum inverting circuit using same
EP0713298A2 (de) 1994-11-21 1996-05-22 Sony Corporation Sender und Zweiwegfunkgerät
US5970102A (en) * 1996-08-24 1999-10-19 Samsung Electronics Co., Ltd. Circuit and method for detecting frequency correction burst in TDMA digital mobile communication system
US6266361B1 (en) * 1998-07-21 2001-07-24 Chung-Shan Institute Of Science And Technology Method and architecture for correcting carrier frequency offset and spreading code timing offset in a direct sequence spread spectrum communication system

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20110182410A1 (en) * 2008-05-22 2011-07-28 Vladimir Yegorovich Balakin Charged particle cancer therapy beam path control method and apparatus
US20110180720A1 (en) * 2008-05-22 2011-07-28 Vladimir Yegorovich Balakin Charged particle beam acceleration method and apparatus as part of a charged particle cancer therapy system
US8841866B2 (en) 2008-05-22 2014-09-23 Vladimir Yegorovich Balakin Charged particle beam extraction method and apparatus used in conjunction with a charged particle cancer therapy system
US8901509B2 (en) 2008-05-22 2014-12-02 Vladimir Yegorovich Balakin Multi-axis charged particle cancer therapy method and apparatus
US9058910B2 (en) 2008-05-22 2015-06-16 Vladimir Yegorovich Balakin Charged particle beam acceleration method and apparatus as part of a charged particle cancer therapy system

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Publication number Publication date
NO20020839D0 (no) 2002-02-20
WO2001015315A8 (de) 2001-06-07
ATE281709T1 (de) 2004-11-15
EP1212830A1 (de) 2002-06-12
EP1212830B1 (de) 2004-11-03
AU6463800A (en) 2001-03-19
WO2001015315A1 (de) 2001-03-01
DE19939811A1 (de) 2001-02-22
NO20020839L (no) 2002-04-22
DE50008531D1 (de) 2004-12-09
CN1382320A (zh) 2002-11-27

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